Background: Increasing antimicrobial resistance among bacterial pathogens has prompted attempts to develop new antimicrobial agents active against multidrug-resistant Gram-positive pathogens.
Objectives: To evaluate the in vitro activity of daptomycin against a worldwide collection of clinical bacterial isolates.
Methods: Daptomycin is a novel cyclic lipopeptide recently approved by the United States Food and Drug Administration. Daptomycin and selected comparators were tested against 6737 clinical Gram-positive strains from more than 70 centres located in Europe, North America and South America.
Results: The overall distribution of daptomycin MIC values were in the range < or = 0.12-8 mg/L and 99.4% of all strains were inhibited at < or = 2 mg/L. Despite resistances to other antimicrobial agents, >99.9% of staphylococcal isolates were inhibited at < or = 1 mg/L of daptomycin (MIC90 0.5 mg/L for staphylococci). Streptococcal isolates were very susceptible to daptomycin independent of their susceptibility to penicillin. MIC50/90 values were < or = 0.12 and 0.25 mg/L, respectively. Enterococci showed the highest daptomycin MIC values, but all isolates tested were inhibited at < or = 4 mg/L (except for one Enterococcus faecium isolate which showed a daptomycin MIC of 8 mg/L).
Conclusions: Daptomycin exhibited excellent in vitro activity against a wide spectrum of Gram-positive organisms and may represent a therapeutic option for infections caused by multidrug-resistant pathogens worldwide.